[CentOS] Monitor disc write in preparation for move to Solid State Disc

I am planning on changing/upgrading one of my systems to Centos 6.x with a
solid state system drive and conventional 'data' drives. Any suggestions for
a good simple tool, or way to give ongoing monitoring of writes to files on
what will become the system drive. The I can then move as much as possible
of the changeable files to the data drives.

Suggestions much appreciated.

regards
Brian